Comparative analysis of drug release kinetics in polyethylene oxide and xanthan gum matrices with various excipients

This study aimed to investigate the effect of various pharmaceutical excipients on the drug release kinetics of extended-release formulations composed of polyethylene oxide (PEO) and xanthan gum (XG), using propranolol hydrochloride (PPN) as the model drug. The formulations contained different ratios (1 : 3, 1 : 1, and 3 : 1 w/w) of PEO or XG to either lactose, dibasic calcium phosphate (DCP), or microcrystalline cellulose (MCC). Compaction analysis revealed that formulations that contain higher excipient content exhibit increased porosity and decreased hardness values. Contact angle measurements indicated that formulations with higher excipient content, particularly with lactose, displayed lower contact angles, which is indicative of increased hydrophilicity. After the in vitro dissolution studies were conducted, the dissolution efficiency (DE), mean dissolution time (MDT), mean dissolution rate (MDR), and similarity factors (f₂) were analysed. The findings showed that a higher amount of lactose in both PEO and XG formulations resulted in faster drug release, with the PEO : lactose 1 : 3 ratio achieving the highest DE (64 ± 8%) and the shortest MDT (77 ± 10 min). Similarly, the XG : lactose 1 : 3 ratio exhibited the highest DE (61 ± 2%) and fastest MDR (0.20 ± 0.01% min⁻¹), although the effect was less pronounced compared to PEO formulations. The kinetic analysis showed that most PEO formulations followed the Peppas model, indicating non-Fickian transport driven by both diffusion and polymer erosion mechanisms. However, most of the XG formulations followed the Higuchi model. The similarity factors (f₂) revealed the influence of excipient type and ratio on the dissolution profiles. Formulations containing a higher amount of MCC displayed higher similarity with the pure polymer profiles. These results give important insights into how excipients can be used to optimise polymeric matrices to regulate drug release in extended-release formulations.